Today, twenty people per square mile. The University of Houston's College of Engineering
presents this series about the machines that make our civilization
run, and the people whose ingenuity created them.

I was born on a planet with two billion other people.
Now I share Earth with almost seven billion others. Together, we
occupy about four hundred million square miles of dry land. That means fewer
than twenty people (on average) occupy each square mile. That sounds like a
lot of room until we realize that life in many huge areas, like the Sahara or
Antarctica, has its drawbacks.

Roughly 1/2 person per linear foot

So let's see how all these people are distributed. Look at, say, arid Nevada
here in the US. It has over two and a half million people and a population
density of 24 people per square mile. That's close to the world average; but
78 percent of those people live in Las Vegas.

Elsewhere, Nevada's density is only five people per square mile; and they almost
all live in a few small cities. Take White Pine County. It's seven times the
size of Rhode Island. Discounting those who live the county seat of Ely, the
rest live on about two square miles each. (Imagine only ten total people living
on Manhattan instead of the actual density -- 71,000 per square mile.)

Our big agricultural states tend to be near the world average or fewer. Nebraska
has 23 people per square mile, but South Dakota has only around ten. And the
population density in Saskatchewan, Canada's bread basket, is fewer than two
people per square mile.

Now, compare those farmlands with our crowded East Coast. Massachusetts and New
Jersey hold about a thousand people per square mile. The population densities of
England, Korea and Japan, each with a great deal of coastline, are all high -- around 400.

So what does this tell us? First of all, that inland life becomes less hospitable.
Life is hard in Russia, with eight people per square mile, or landlocked Tibet with
only two. Of course, the very desirability of coastal regions makes life hard in
another way. They become populated beyond the capacity of their adjacent land to
sustain them. Bangladesh, with almost three thousand people per square mile, suffers
constant food shortages.

All this evokes the huge question hovering over us. What's Earth's real capacity for
housing us? How many people can our environment survive in the long run? The answer
depends on the quality of life the population enjoys. For our standard of living the
number would probably be a lot fewer than now live. Those conversations carry vast
political baggage, and I won't try to argue them here. But I do notice something:
Where population density is low, so too is the tendency to worry about such matters.

For the moment, I only ask you to consider the odd way we distribute ourselves on our
planet. It's like a cocktail party: Fifty out of sixty people in a large house may
always be found in one room or another at any moment. By the same token, I never cease
to wonder at the empty vastness of Texas whenever I leave Houston's close-knit camaraderie.

I'm John Lienhard at the University of Houston,
where we're interested in the way inventive minds
work.

(Theme music)

The statistical information herein can easily be found in Wikipedia. Simply Google
the name of the town or country followed by Wiki to get the data. A sidebar on
the right will almost always give the area, population, and population density.